A tourbillon mechanism is a device intended to average the running deviation of the positions of the balance of a timepiece. In the present invention, such a tourbillon comprises the traditional tourbillon comprising a tourbillon carriage as well as the carousel. To that end, a tourbillon includes a support (for example, a carriage in the case of the traditional tourbillon) pivotably mounted on the frame, in general an assembly formed by a bar and a plate and, pivotably mounted on the support, a sprung balance and an escapement in particular including an escapement wheel provided with a disc and a pinion. The support includes a gear kinematically connected to the going train of the timepiece, in general to the mean disc. A toothed wheel, mounted fixed on the frame, meshes with the escapement pinion. In this way, each time the balance is in position to receive a driving impulse from the escapement, the torque applied by the mean disc on the gear causes the support to rotate slightly, the impulse from the balance being given by the escapement whereof the wheel turns by meshing of its pinion with the toothed disc. The discs and pinions are generally arranged and numbered such that the tourbillon performs one revolution per minute. Thus, when the timepiece is positioned vertically, the position of the dead point of the balance therefore performs one revolution per minute, which averages the running deviations in the vertical positions. However, the lag between the horizontal and vertical positions remains.
Different solutions have been proposed to offset this drawback.
Known for example is a tri-axial tourbillon described in application EP 1,574,916, comprising a carriage containing the balance and the escapement rotating along an axis, the carriage being mounted in a second carriage so as to be able to rotate around the axis, the second carriage being rotatably mounted in turn in a third carriage rotating around a stationary axis relative to the timepiece, the three axes being perpendicular to one another. The tri-axial tourbillon is driven by a driving disc mounted on the plate of the timepiece, which drives a pinion secured to the third carriage, and causes the carriage to rotate around its axis, thereby setting a pinion in rotation meshing with a crown fixed on the plate of the timepiece, which rotates the carriage around its axis, the second carriage setting the first carriage in rotation around its axis by means of a crown and the fourth-wheel pinion secured to the third carriage, and thus to transmit the energy coming from the drive disc to the assembly formed by the escapement pinion, the escapement disc and the balance placed in the first carriage.
Such a mechanism has the drawback of being bulky and not very aesthetically pleasing due to the presence of several toothed crowns appearing on the dial side.
Also known is a differential correction device described in application EP 2,031,465. This device comprises several supports pivotably mounted around respective articulation axes, which makes it possible to neutralize the movements of a transmission train around two or more axes. The aim of this mechanism is to keep the seat of the support bearing the adjusting system in a constant position irrespective of the position of the frame. The isochronism faults of the system are eliminated, given that the oscillating system has only one position. Such a mechanism does not have the same aims as a tourbillon mechanism, which makes it possible to further reduce the running differences between horizontal and vertical positions of a timepiece comprising such a tourbillon mechanism.
One aim of the present invention is therefore to offset these drawbacks, by proposing a timepiece comprising a tourbillon mechanism making it possible to further reduce the running differences between horizontal and vertical positions.
Another aim of the present invention is to propose a timepiece comprising a tourbillon having a reduced bulk and improved aesthetic appearance.